Speaker: Kate Cassity-Duffey, University of Georgia Department of Horticulture
Recorded introduction: Narrated by Bethany Harris
Moderator: Gabrielle LaTora, Agriculture and Natural Resources Agent, Fulton County, Georgia
Webinar Date: July 23, 2026
Duration: 20:18
Segment: 04 of 08
Series: Cut Flower Symposium
CEU Categories: [PENDING]
About This Session
Kate Cassity-Duffey opens by telling the room this is part one of her talk, moved up because of technical issues, and that she will cover snapdragons rather than the sunflowers and lisianthus her recorded introduction has just promised. She is a soil scientist by training who reached cut flowers through organic vegetable growers, many of whom now grow flowers as a value-added product beside CSA shares and farmers market sales.
Two problems frame the work. Field production in the South shortens stems and leaves damaged or tattered flowers, against a commercial grade of roughly 60 centimeters for most cut flowers. Organic fertility is the harder problem, and it is her specialty. Nitrogen arrives as poultry manure, compost, or feather meal and has to pass through mineralization and then nitrification before a plant can take it up, while immobilization, nitrate leaching, and ammonia volatilization remove some along the way. A University of Maryland Extension document is the only fertility guidance she names, and she says outright that cut flower growers may be under-fertilizing.
The first trial sets a high tunnel against the field on a December 1 plant date, using Madame Butterfly Bronze with White and Chantilly Bronze, about a hundred plants per plot replicated four times. First harvest date did not differ between the two, which surprised her, since flowering answers to light as well as temperature. Nearly everything after that did. Chantilly ran about 15 days of harvest in the field against eight in the tunnel, Madame Butterfly about two weeks against ten days, and tunnel stems came in about 10 centimeters longer for both cultivars. The tunnel also loosened the spikes, with flowers spreading down the stem, which she ties to a winter that swung between the 80s and 20 degrees.
The second trial puts a January 7 plant date against March 11 across eight Johnny’s cultivars, fertilized at 100 pounds of nitrogen at planting plus 50 side-dressed at midseason, with potassium as potash because southern soils leach it quickly. Sixty days between plantings did not buy 60 days between harvests. The March date gave three to four stems per plant against two, though a few stems ran thick enough to bother a florist. Four chat questions close the segment.
The Eight Cultivars, With Stem Lengths
Cassity-Duffey walks the plant date trial cultivars one at a time between 11:47 and 14:34, with her own field observations. Stem length is the figure she returns to most, because it decides which buyers a stem can serve.
| Cultivar | Group | Stem length as given | Her note |
|---|---|---|---|
| Antibes Apricot I | one | short | Beautiful plump flower, nice coloring. Not particularly recommended for summer production, so it suited the January date. |
| Avignon Lavender 2 | two | around 50 cm | Beautiful color, wonderful scent, staggered harvest. |
| Avignon Apricot | not stated | short | Her favorite, for a butter yellow much deeper than the seed catalogs showed. Some undesirable flopping where stems were not strong. |
| Potomac Orange | three or four | not stated, good strong stem | Later harvest window, very vibrant color, and what she calls a very long vase life in her not-scientific observation. |
| Chantilly Light Salmon | not stated | not stated | A nice go-to. Many stems per plant, continuous harvest through the year, a stock-like bloom, hardy and uniform flowering time. |
| Cannes Light Bronze | not stated | 60 to 65 cm | Beautiful color, good stem length and height, harvest a little more stretched out. |
| Potomac Lavender | three or four | not stated | Did okay. Later flowering date in the region, and the flower at the top not fully full on the plant date she chose. Very fragrant, sometimes bigger stems. |
| Costa Summer | not stated | 65 to 70 cm | Very strong stems, nice flower development, super tall, opening into a much lighter color with a beautiful gradient. |
Where a column reads “not stated,” she did not give the figure on camera. Nothing has been supplied from outside the recording.
Chapters (Video Timestamps)
| Time | Chapter |
|---|---|
| 0:00 | Introduction and Recorded Bio |
| 0:36 | Part One, and Why Snapdragons |
| 1:32 | Why Organic Growers Are Adding Cut Flowers |
| 2:12 | High Tunnel or Field, and Why the South Is Hard |
| 3:20 | Organic Fertility and the Maryland Gap |
| 3:53 | The Nitrogen Cycle, and Why Organic Is Harder |
| 5:28 | Trial One: High Tunnel Versus Field, and the Rating Scale |
| 6:48 | Results: Same First Harvest, Different Last |
| 8:01 | Harvest Duration: Fifteen Days Against Eight |
| 8:40 | Stem Length, Density, and a Strange Winter |
| 9:41 | High Tunnel Versus Field Takeaways |
| 10:30 | Trial Two: Two Plant Dates, and the Fertilizer Rates |
| 11:47 | The Eight Cultivars, One by One |
| 13:48 | Potomac Lavender and Costa Summer |
| 14:34 | Plant Date Results and Stems Per Plant |
| 15:57 | Takeaways, Year Two, and Contact |
| 17:24 | Q&A: Seeding Potomac Now for a Fall Bloom |
| 18:11 | Q&A: Same Cultivars in Year Two |
| 18:37 | Q&A: Spacing and Rows Per Bed |
| 19:07 | Q&A: What the Snapdragon Groups Mean |
Questions and Answers
Q: Why is this talk about snapdragons when the program lists sunflowers and lisianthus?
A: Cassity-Duffey says at 0:42 that technical issues moved her up and she is giving part one of her presentation. She asks the audience to come back to her for the second part, on lisianthus and sunflowers, “after around the 11.” That second part does not appear on this recording.
Q: Why is organic fertility harder to manage than conventional fertility?
A: Organic nitrogen arrives in a complex form, as poultry manure, compost, or feather meal, built of large amino acids and carbon chains. It depends on mineralization by soil microorganisms to break down into plant-available ammonium, and then on nitrification to become plant-available nitrate. Both are microbially mediated. At the same time the system loses nitrogen three ways: immobilization, where soil microbes compete with the crop for what is available; nitrate leaching, where rain or irrigation pushes it below the root zone; and ammonia volatilization, the gaseous loss from soil to atmosphere. Predicting how much becomes available means predicting all five processes at once.
Q: Did the high tunnel move the first harvest date?
A: No, and she says she was really surprised by that. The trial ran a December 1 plant date with Madame Butterfly Bronze with White and Chantilly Bronze, about a hundred plants per plot replicated four times, rated 1 to 10 on stem length, inflorescence length, and density. Both cultivars hit the same first harvest date in the field and in the tunnel. She reasons that flowering is not driven by temperature alone but by light as well. She does note about a week’s difference in first harvest between Chantilly and Madame Butterfly.
Q: How much did the high tunnel shorten the harvest window?
A: For Chantilly, about 15 days of harvest in the field against about eight days in the high tunnel. For Madame Butterfly, about two weeks in the field against more than ten days in the tunnel. Her framing: a high tunnel suits a grower who wants a rapid, uniform harvest, and the field suits one who wants the harvest stretched out.
Q: What happened to stem length, and what did the tunnel cost in exchange?
A: Field stems ran about 10 centimeters shorter than high tunnel stems, about four inches, in both cultivars, and she calls stem length the point that depends on who your market is. The tunnel charged for it in density. Flowers began stretching out along the stem rather than sitting compactly, so even with good quality and long stems, especially in the Chantillys, some ran down toward the bottom and the spike was less dense. She attributes most of that to a winter that put February in the 80s and swung back to 20 degrees, and thinks high temperatures in the tunnel worsened it.
Q: What fertility went on the plant date trial, and why do the rates look high?
A: 100 pounds of nitrogen at planting, then 50 pounds side-dressed about halfway through the growing season, plus a good bit of potassium as potash because potassium leaches quickly in southern soils. She flags the rates as possibly seeming high and explains that organic fertilizer releases over time at a different rate than conventional, so not all of it is available immediately.
Q: Which cultivars had short stems and which had long ones?
A: On the short side, Antibes Apricot I, which she liked for its plump flower and coloring, and Avignon Apricot, her favorite for its butter yellow, both of which she calls out for shorter stems and for the flopping that follows when stems are not strong. Avignon Lavender 2 ran around 50 centimeters. On the long side, Cannes Light Bronze at about 60 to 65 centimeters and Costa Summer at 65 to 70 centimeters with very strong stems. Potomac Orange had a good strong stem and what she describes as a very long vase life in her not-scientific observation.
Q: Did planting two months apart give harvests two months apart?
A: No. She underlines that the plant dates were 60 days apart while the harvest windows were not, and tells growers doing succession planting to think about growing degree days and light rather than calendar spacing alone. Harvest for the first plant date started around late April, with the second closer to May.
Q: How many stems per plant did each plant date give?
A: The January plant date came in at about two stems per plant, which she found interesting because those plants were pinched and she expected more branching. The March plant date ran closer to three to four. Her summary is a shorter window on the later date, but more stems per plant. Bloom quality did not differ much between the two, and overall rating was similar; stem length was fairly consistent, with the longer stems on the second plant date.
Q: Can snapdragons started from seed now bloom in late fall, specifically Potomac?
A: She calls it an excellent question and one she has herself, and says she knows some growers are doing it and that she will start one in August to find out. Her estimate is about 10 weeks from seed until transplant, and with light being the deciding factor she would imagine a fall bloom. She adds that following the groups matters, and says she thinks Potomac is a group one. A participant then corrects this in the chat at 19:43, giving Potomac as typically a three to four, and she accepts the correction on air. Her own cultivar walk puts Potomac Orange and Potomac Lavender in group three or four.
Q: How were the snapdragons spaced?
A: Four inch spacing, which she describes as a little bit closer, with four rows per plot on three foot centers.
Q: What do the snapdragon groups mean?
A: The groups give an index of when a cultivar performs best and of flowering time. Group ones are typically cooler and faster; group twos and threes run a little longer. She has also noticed cultivars described as groupless, and names Madame Butterfly as one, saying she does what she wants. In lisianthus, she adds, higher groups tend to give longer stems because of the longer growing time, and a grower can stagger group one against group two to move from cool into longer seasons.
Resources Named on Camera
- University of Maryland Extension document on cut flowers, which she calls up at 3:30 as helpful but silent on how much fertility to apply. No title or web address is spoken.
- Johnny’s, the seed source for the eight-cultivar plant date trial. She says at 11:40 that the cultivars are commonly grown ones plus ones Johnny was interested in seeing grown in the southern region.
- American Takii, thanked alongside Johnny’s Seeds at 17:00.
- Her email address, which she says at 17:03 is “at the bottom” of the slide, with an invitation to growers to write anytime, especially organic producers. No address is spoken on the recording.
Publication Notes
Two things must be supplied by hand before this page goes live.
- Her email address. She points at it on a slide and never reads it. Nothing in the recording can recover it, so it has to come from the speaker or the symposium organizers.
- The CEU categories. Credit was offered at the live symposium and the categories were never supplied to the archive team. This holds across every Cut Flower Symposium segment processed so far, and it should be back-filled in one pass rather than segment by segment.
The session title is built from the delivered content. The printed agenda and her own recorded bio both promise field-grown sunflowers and lisianthus, and she delivers neither. Publishing under the agenda title would send growers looking for content that is not on the recording. Her line at 16:52 about coming back “after around the 11” refers to a slot that went to a different speaker, so there is no part two to link to.
The Potomac group question is left as an exchange, not resolved. She states group one, a participant corrects it in chat, she accepts the correction, and her own cultivar walk agrees with the correction. Any edit that reduces this to a single number will misstate the recording.
“Antibes Apricot I” and “Avignon Lavender 2” are inconsistent on purpose. The Roman numeral was confirmed against the recording during the Stage 1 sweep; the arabic numeral was never in doubt and both transcription engines produced a digit. If the slide deck ever surfaces, one look settles whether both should be Roman.
Scaling Note
Target. Stage 3 derives from the Stage 2 package. Segment 03’s website version ran 25.6 KB against an 18.2 KB archive summary, a ratio of 1.41. This archive summary is 15.0 KB, so the proportional target was about 21 KB.
Delivered. 15.5 KB, a ratio of 1.06 against segment 03’s 1.41. The file came in under target rather than at it, and the reason is worth recording: the cultivar table replaced what would otherwise have been eight paragraphs of prose, and it is both shorter and easier to use. A grower comparing stem lengths reads a column, not a page.
What was added rather than condensed. The cultivar table has no counterpart in the Stage 2 package. It reorganizes content already in the Q&A and the chapter walk into the form a website reader wants, which is what the website version is for. No content in it comes from outside the recording, and the “not stated” cells are honest gaps rather than omissions.
Processed for UGA Center for Urban Agriculture / Cut Flower Symposium Archives
Source: Stage 2 Archive Package, GTBOP_Archive_Summary_2026-07-23_CassityDuffeySnapdragons.md